I've got a model which calculates categories ('negative growth', '0-1% growth', '1-5%' growth', 'above 5% growth') for a number of stores and is then fed into Tableau.

I assign shapes/colors to these different values to have red downward arrows, green upward arrows etc.

The issue is that I currently don't have stores with negative growth, and I have no 'write' access to the data, but I must publish the dashboard on server and make sure that the right arrow appears if I have stores with negative growth that appear in scheduled refreshes.

It's not possible to add a placeholder to the data if there is no data whether with the original dimension or measure of the data source. One way to test though would be to copy and paste the data from the underlying data into Excel or text file. Then, add a sample data that would show negative growth. Then, edit the connection in Tableau to point at this 'sample file.' Hopefully this helps!